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Introduction to Pathology DR:Gehan mohamed

Introduction to Pathology DR:Gehan mohamed. Definition of pathology. It is the “ Scientific study of disease" . "scientific study of the molecular, cellular, tissue, or organ system response to injurious agents.".

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Introduction to Pathology DR:Gehan mohamed

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  1. Introduction to PathologyDR:Gehan mohamed

  2. Definition of pathology It is the “Scientific study of disease" . "scientific study of the molecular, cellular, tissue, or organ system response to injurious agents." Pathology serves as a "bridge" or "link" between the preclinical sciences (anatomy, physiology, ……etc.) and the courses in clinical medicine.

  3. 2. Classification: Autopsy Biopsy Cytology (1) Human pathology (2) Experimental pathology

  4. Seven Branches of Pathology • General Pathology • Systemic Pathology • Surgical Pathology • Gross Pathology • Cellular Pathology • Clinical Pathology • Immunopathology

  5. General Pathology • Common changes in all tissues. e.g.. Inflammation, cancer, ageing, edema, hemorrhage ….etc. • Systemic Pathology • Discussing the pathologic mechanisms in relation to various organ systems e.g. CVS, CNS, GIT…..etc.

  6. Techniques of Pathology 1. Human pathology (1) Autopsy (2) Biopsy (3) Cytology: smear, fine needle aspiration 2. Experimental pathology (1) Animal experiment: animal model (2) Tissue and cell culture

  7. Necropsy: Gross examination of the animal cadaver by systematic dissection in order to evaluate any abnormal changes (lesions) that may be present. • Autopsy: Synonymous to necropsy in human medicine • Biopsy: Removal and examination of tissue obtained from the living body

  8. What is the Disease? • It is the “State in which an individual exhibits an anatomical, physiological, or biochemical deviation from the normal” • Disease may be defined as : • an abnormal alteration of structure or function in any part of the body.

  9. Classification of Diseases: • (A)Developmental – genetic, congenital. • (B)Acquired: (1)Inflammatory – Trauma, infections, immune, etc. (2)Neoplastic – tumors cancers (3)Degenerative – ageing. (4)Metabolic. (5)Iatrogenic: Drug induced.

  10. What should we Know About A Disease • Definition. • Epidemiology – Where & When. • Etiology – What is the cause? • Pathogenesis - Evolution of dis. • Morphology - Structural Changes • Functional consequences • Management • Prognosis • Prevention Pathology

  11. Etiology “Study of the cause of a disease" Knowledge of etiology remains the backbone of: • Disease diagnosis • Understanding the nature of diseases • Treatment of diseases.

  12. Etiology “Study of the cause of a disease" An etiologic agent: is the factor (bacterium, virus, etc.) responsible for lesions or a disease state. Predisposing Causes of Disease: Factors which make an individual more susceptible to a disease (damp weather, poor ventilation, etc.) Exciting Causes of Disease: Factors which are directly responsible for a disease (hypoxia, chemical agents , virus, bacteria …. etc.). 

  13. Disease Disease Disease Disease Disease Etiology • One etiologic agent several diseases, as smoking. • One etiologic agent - one disease, as Malaria. • Several etiologic agents one disease, as cancer .

  14. Pathogenesis The sequence of events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease.

  15. CELLS Response to injurious agent Either : • ADAPTING • SUSTAINING REVERSIBLE INJURY • SUFFERING IRREVERSIBLE INJURY AND DYING

  16. Clinical Symptoms & Signs • Clinical symptomsare the patient’s complain usually by its own words as pain. • Clinical signs are seen only in the living individual as organomegaly.

  17. MORPHOLOGY Morphology remains at the heart of diagnostic pathology. • Morphologic change Characteristic of the disease Diagnostic of the etiologic process • Functional derangements

  18. Morphology (1)Gross appearance: size, shape weight color consistency surface edge, section

  19. (2)Microscopic examination for tissue sections fixed in formalin then stained by HE (hematoxylin and eosin) to be examined by light microscope for Histologic and cytologic changes. Hemangioma

  20. Histochemistry using PAS stain PAS→BM

  21. Immunohistochemistry 1. Ag-Ab specific reaction 2. Applications : in diagnosis of tumor histogenesis

  22. Leiomyosarcoma Actin (+)

  23. (3)Ultrastructural observation By using electron microscope) Filtering membrane

  24. Podocyte SEM (scanning electron microscope)

  25. (4)Flow cytometry (FCM) In neoplastic diseases Can determine : 1- If there is One kind of cells→quantitative assesment 2. DNA ploidy analysis (amount of DNA)

  26. （5）Image analysis (IA) it can determine Nuclear diameter; circumference; area; volume; morphology

  27. （6）Molecular biology technique 1. Polymerase chain reaction (PCR) 2. DNA sequencing

  28. Polymerase chain reaction (PCR)

  29. prognosis • Expected outcome of the disease, It is the clinician's estimate of the severity and possible result of a disease. 

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